LIPID CHEMISTRY Flashcards
1
Q
what is a lipid?
A
a lipid is an organic molecule that isn’t soluble in water but soluble in organic solvents such as ether , chloroform , benzene , methanol , ethanol , etc.
2
Q
describe the water molecule
A
the water molecule is inorganic and polar
3
Q
lipids are …
A
non - polar
4
Q
list the 4 major classes of biomolecules
A
lipids
carbohydrates
proteins
nucleic acids
5
Q
what do lipids make?
A
human membranes and the bilayer[ mainly made up of lipids]
6
Q
lipids are essential components in all living organisms such as :
A
animals , plants , insects , bacteria , fungi , etc.
7
Q
compare lipids to carbohydrates and protein
A
lipids are lighter than carbs & proteins. 1 g lipid or fat provides 9kcal energy
1 g protein or carb provides about 4 kcal energy
8
Q
list the lipids and their derivatives.
A
vegetable oil , butter , margarine , grease , wax , etc.
steroid hormones , fat soluble vitamins , prostaglandins , thromboxanes , leukotrines are also lipids or lipid derivatives
9
Q
discuss the insulation function of lipids.
A
mammals , especially aquatic mammals , have most fat deposited subcutaneously[ situated or applied under the skin] which act as an insulating material to protect their body from extreme heat
10
Q
discuss the energy function of lipids.
A
camels have a hump on their backs’ , a large deposition of fat[mostly triacylglycerol or triglyceride] that provides energy and water during long - term starvation[ 1 g fat provides 9 kcal energy and 1 g of water]
11
Q
what is the function of creams that contain lipids?
A
creams that contain lipids prevent loss of moisture from our skin
12
Q
what does the lipid coating in the birds’ feathers do?
A
the lipid coating in birds’ feathers protects their feathers and prevents the feathers from getting wet
13
Q
why do lipids coat the leaves of plants?
A
to protect from against abrasion and curb the loss of moisture by evaporation
14
Q
What do lipids work as?
A
Lipids work as s precursor of several hormones and some fat soluble & anti-oxidant vitamins[A,D,E & K]
15
Q
What are lipids a crucial part of?
A
Lipids are a crucial part of the plasma membrane
16
Q
Where are lipids found?
A
lipids are present in the kidneys , heart , liver , etc.
17
Q
Lipids are found in associate with protein called lipoproteins. What do these lipoproteins work as?
A
These lipoproteins work as transporters of lipids
18
Q
Lipids are an integral part of …
A
cell membrane
19
Q
Lipids are classified into 5 major classes based on physical property. List the 5 major classes of lipids.
A
- fatty acids and their derivatives
- neutral esters of fatty acids and glycerols[glycerides]
- ionic esters of fatty acids , glycerols and phosphoric acids[phospholipids]
- lipids without glycerols[sphingolipids]
- lipids combined with proteins e.g. lipoproteins , glycolipids , cholesterol , etc.
20
Q
What group must fatty acids contain?
A
a carboxylic[-COOH] group
21
Q
What do fatty acids contain?
A
Fatty acids contain two ends – one hydrophilic / polar end and another hydrophobic / non-polar end
22
Q
Why are fatty acids called amphiphilic compounds?
A
Fatty acids are hydrophilic and hydrophobic
23
Q
Where is the carboxylic group located?
A
The Carboxylic group (-COOH) is located at the hydrophilic end
24
Q
where is the hydrocarbon tail located?
A
the hydrocarbon tail is located at the hydrophobic end -which may contains carbon-carbon single (-C-C-) or double (-C=C-) bonds
25
How many carbons can a hydrocarbon tail have?
12 - 20 carbons
26
Classification of Fatty acids based on the type of carbon - carbon bond in the hydrocarbon chain:
Saturated fatty acids
| Unsaturated fatty acids - monounsaturated fatty acids , polyunsaturated fatty acids
27
Describe saturated fatty acids at room temperature.
saturated fatty acids are solid and waxy at room temperature
28
what are saturated fatty acids rich in?
animal originated fat
29
what is the general formula of saturated fatty acids?
[(CnH2n+1)COOH]
30
What type of carbon - carbon bonds do saturated fatty acids contain?
ONLY single carbon - carbon bonds
31
what are free fatty acids[FFA] ?
Fatty acids which are not in esterified form
32
Most fatty acids are present in ...
esterified form with glycerols
33
what is the carbon number in saturated fatty acids ?
2 - 24
34
smaller than 10 carbons fatty acids are not normally found in animal lipids. what is the exception?
butyric acid (CH3-CH2-CH2-COOH)
35
Give 2 examples of saturated fatty acids.
Palmitic acid[C16:0] , Stearic acid[C18:0]
36
Define the term unsaturated fatty acids
unsaturated fatty acids are fatty acids that contain at least one carbon - carbon double bond
37
The higher the double bonds , the lower the ...
melting or boiling points
38
the solubility of unsaturated fatty acids in non - polar solvents are also better than their...
saturated counter parts
39
The melting or boiling points[of unsaturated fatty acids] are lower than those of ...
their saturated counter parts
40
describe all common unsaturated fatty acids.
All common unsaturated fatty acids are liquid at room temperature
41
what does the total number of carbon-carbon double bonds denote?
The total number of carbon-carbon double bonds denotes the degree of unsaturation
42
list the types of polyunsaturated fatty acids.
* Dienoic series (two – C-C – double bonds)
* Trienoic series (three – C-C – double bonds)
* Tetranoic series (four – C-C – double bonds)
* Pentanoic series (five – C-C – double bonds)
* Hexanoic series (six – C-C – double bonds)
43
how many carbon - carbon double bonds does a monounsaturated fatty acid contain?
1
44
where are monounsaturated fatty acids present?
monounsaturated fatty acids are present in the lipids of prokaryotic cell membranes
45
list 2 examples of monounsaturated fatty acids and their molecular formula
plamitoleic acid-C15H31COOH
| oleic acid - C17H33COOH
46
give a description of a dienoic series
a dienoic series contains 2 carbon-carbon double bonds
example - linoleic acid[C18:2 , ∆9,12]
Melting point is -5 degrees celsius
47
give a description of a trienoic series
a trienoic series Contains three carbon-carbon double bonds
Such as- α-Linolenic acid (C18:3, ∆9,12,15)
γ-Linolenic acid (C18:3, ∆6,9,12)
Melting point is -10 degrees celsius
48
Give a description of a tetranoic series
a tetranoic series contains 4 carbon - carbon double bonds
Such as- Arachidonic acid (C20:4, ∆5,8,11,14)
Melting point is -50
degrees Celsius
49
give a description of a pentanoic series
a pentanoic Such as- Eicosapentaenoic acid (C20:5, ∆5,8,11,14,17)
Melting point is -50 degrees Celsius
50
give a description of a hexanoic series
Contain six carbon-carbon double bonds
Such as- Docosahexanoic acid (22:6, ∆4,7,10,13,16,19)
Melting point is -50 degrees Celsius
51
what are essential fatty acids?
fatty acids that can't be produced in the human or animal body
52
what are humans and animals dependent on for essential fatty acids?
Humans and animals are completely dependent on plants for these fatty acids
53
list the 2 essentials fatty acids.
```
Linoleic acid (18:2, ∆9,12)
α-Linolenic acid (18:3, ∆9,12,15)
```
54
What are plant desaturase enzymes capable of doing?
plant desaturase enzymes are of providing double bonds at the ∆12 and ∆15 positions which are not possible by animal desaturase enzymes
55
where are unsaturated fatty acids synthesized?
Unsaturated fatty acids are synthesized from their saturated equivalents
56
First , saturated fatty acids are biosynthesized. when and how are double bonds introduced to the chain?
double bonds are introduced later in various positions
57
Human and animal system cannot introduce double bonds beyond the..
∆9 position
58
What are eicosanoids?
Eicosanoids are the derivatives of 20 carbon arachidonic acid (20:4, ∆ 5 , 8 , 11 , 14)
59
name the 3 major classes of eicosanoids.
* Prostaglandins (PG)
* Thromboxanes (TX)
* Leukotrines (LT)
60
where are prostaglandins[PG] synthesized?
In all mammalian cells except red blood cells[RBC]
61
where has prostaglandin synthesis been recorded?
Prostaglandin synthesis has been recorded in crustaceans, insects, amphibians, fish, and mammals but not in prokaryotes and lower class eukaryotes such as yeast
62
Prostaglandins[circulating hormones) aren't stored[unlike insulin]. How long are prostaglandins produced after a stimuli?
Prostaglandins are produced within 10-30 seconds after a stimuli
63
Chemistry. what do prostaglandins contain?
Prostaglandins contain diverse groups such as keto (=C=O), carboxyl (-COOH), hydroxyl (-OH) which are found on the side chain or cyclopentane ring in the structure
64
Prostaglandins are the derivatives of :
prostanoic acid
65
The double bonds of prostaglandins are in the :
TRANS configuration
66
what does the letter after the abbreviation PG indicate?
The letter occurring after the abbreviation PG (such as PGE) indicates the nature of the oxygen containing substituents present in the cyclopentane ring
67
What the number in PGE2 represent?
The number 2 in PGE2 indicates that there are two double bonds present in the hydrocarbon side chains
68
what are the physiological effects of prostaglandins?
They cause confusion
69
what do prostaglandins usually work as?
Prostaglandins usually work as a natural mediator of fever, pains and inflammation such as- arthritis, skin or eyes inflammations etc.
70
what does the release of prostaglandins in eyes after eye inflammation do?
Release of prostaglandins in eyes after eye inflammation can increase vascular permeability and intraocular pressure
71
what are the effects of prostaglandins blocked by?
The effects of prostaglandins are by corticosteroid or anti - inflammatory drugs which prohibit PG[prostaglandins] synthesis
72
what are the functions of prostaglandins?
* Prostaglandins retain water , transport ion and regulate blood pressure
* A Low tropical dose of some PGs can treat glucoma
73
List the first 3 clinical uses of prostaglandins.
Prostaglandins :
* induce child birth or abortion (PGE2 and PGF2)
* prevent and treat peptic ulcer (PGE)
* Act as a vasodilator during sever ischemia of limb
74
List the last 3 clinical uses of prostaglandins
Prostaglandins
* provides relief from pulmonary hypertension
* treats erectile dysfunction (ED) or penile
* rehabilitation after surgery (PGE1)
75
What is thromboxane[TX] first isolated from?
Thromboxane[TX] is first isolated from blood platelets and also called thrombocyte
76
Where did the name thromboxane come from and what is its abbreviation?
The Name came from the term ‘thrombosis’ and abbreviation is TX (such as TXA2, TXB2)
77
What does thromboxane have?
Thromboxane has a six-membered ring containing an ether
78
what does the letter after TX denote?
The letter after TX denotes the nature of oxygen containing six-membered ring and number after that denotes the number of double bonds
79
what is thromboxane produced by and what does it act in?
Thromboxane is Produced by platelets and act in the formation of blood clots
80
what does thromboxane reduce?
thromboxane reduces blood flow to the site of the blood clot
81
what are the aspirin or aspirin type drugs[that reduce or block the synthesis of thromboxanes] usually used for?
Aspirin or aspirin type drugs, which reduce or block the synthesis of throboxanes, are usually used to relieve from this kind of intravascular thrombosis
82
where are leukotrienes found?
Leukotrienes are found in the White Blood Cells (WBC) or leukocytes
83
What do leukotrienes contain?
Leukotrienes contain
| THREE conjugated double bonds
84
what are leukotrienes derived from and what are they synthesized by?
Leukotrienes are Derived from arachidonic acid (20:4) & synthesized by several oxidase & lipoxyginase (LOX)
85
The abbreviation of leukotrienes is LT and there are many kinds of leukotrienes such as:
LTA4, LTB4, LTC4, LTD4, LTE4 and LTF4
86
what do the letters after LT & the numbers thereafter indicate?
The letters after LT indicate the nature of O2-containing substituents & the number thereafter indicates the number of double bonds
87
what do leukotrienes cause?
Leukotrienes cause the contraction of smooth muscle especially in the lung
88
Leukotrienes may also have inflammatory properties. what are those inflammatory properties involved in?
Those inflammatory properties are involved in rheumatoid arthritis
89
The strong contraction of the smooth muscle of the lungs occurs due to
Potentially fatal allergic reactions caused by leukotrienes
This reaction is more fatal for the person who is hypersensitive to bee stings, penicillin etc.
90
Clinical correlation : where would an asthmatic attack result from?
An Asthmatic attack may result from this contraction function by the synthesis of LTC4.
91
What does the drug that inhibits the synthesis of LTC4 show?
The drug that inhibits the synthesis of LTC4 shows the promising effect for the treatment of asthma and is
used in the inhalers
92
Name the most important reaction of the carboxyl group
esterification
93
briefly describe what takes place in esterification.
In the esterification reaction , one molecule of acid and one molecule of alcohol react reversibly to yield one molecule of water and an ester.
94
In hydrogenation , the h2 may be added across the double bonds on unsaturated fatty acids or their lipid parents in
The presence of Ni, Pt, or Pd catalysts
95
why is the addition of H2 cis?
Both hydrogen atoms of the hydrogen molecule attack the double bond simultaneously.
This occurs because the H molecule is bound to the catalyst surface by unpaired electrons as it is the alkenes (pi bond interactions)
96
example of a hydrogenation acid
For example – linoleic (C18:2,∆9,12) or oleic acid (C18:1,∆9) is converted to stearic acid by hydrogenation reaction.
97
what is hydrogenation?
Hydrogenation is a TEST which may be used to determine unsaturation (number of double bonds) in a sample of fat.
98
what is hydrogenation used in on a large scale? list an example.
On a large scale , hydrogenation is used in the manufacture of margarine. For example – a triglyceride from plant sources (oils) are hydrogenated until they become solids at room temperature and assume the consistency of butter.
99
briefly describe what takes place in ozonolysis.
One mole of ozone (O3) can join with a double bond of an unsaturated fatty acids and initially forms an unstable ozonide with a final product of two aldehydes.
100
briefly describe what takes place during the oxidation by KMnO4[at neutral pH]
At neutral pH, each double bond of an unsaturated fatty acid can be oxidized by KMnO4 to form a cis-Diol.
101
Briefly describe what takes place during the oxidation by KMnO4(at alkaline pH)
At alkaline pH, double bonds of an unsaturated fatty acid can be oxidized by KMnO4 to form a mono- or di-carboxylic acid.
102
Briefly describe what takes place during the oxidation by OsO4(at alkaline pH)
At alkaline pH , the double bonds of an unsaturated fatty acid can be oxidized by OsO4 to form a cis - diol
103
PEROXIDATION OF UNSATURATED FATTY ACIDS. Describe the double bonds in polyunsaturated fatty acids.
The double bonds in polyunsaturated fatty acids are not conjugated
104
What do successive bonds belong to?
Successive bonds belong to a 1,4-pentadiene system
105
what does the 1,4 pentadiene show?
This system shows properties
which differ from those of
conjugated systems where electrons are delocalized
106
what is the 1,4-pentadiene readily attacked by? when does this take place?
The 1,4-pentadiene system is readily attacked by molecular oxygen after generation of a free radical at the methylene.
107
after molecular oxygen is added , what will it be converted to?
After the addition of molecular oxygen it will be converted to a conjugated hydroperoxide which will be finally converted to keto- and hydroxy-keto acids
108
What is this kind of conversion of fats or lipids called?
This kinds of conversion of fats or lipids is called the rancidation which is inversely proportional to its quality
109
what causes fats to be rancid during storage
During storage, fats can be rancid due to peroxide formation at double bonds with atmospheric oxygen or microbial hydrolysis when free fatty acids are released
110
what do short chain fatty acids have?
These short chain fatty acids have some unpleasant odour and taste
111
The higher the amount of short chain fatty ...
The higher the rancidity of the fat
112
How can the rancidity of fats be determined ?
taste or smell
by taste or smell - From the unpleasant taste or smell of fat the qualitative rancidity of fat can be determined
113
How can the rancidity of fats be determined ?
titration reaction
By the titration of the fat with alkali such as KOH and an indicator such as phenolphthalein can quantitatively determine the level of rancidity in fat.
114
How can the rancidity of fats be determined ?
acid value
The result of titration is called ACID
VALUE and the higher the acid
value the lower the quality of fat.
115
Fat is the major component of our cell membrane. what happens if membrane function is defective?
It causes cell death
116
How can humans protect themselves from fat oxidation?
by consuming foods containing anti - oxidants such as Vit-E, Vit-C, Flavonoids, Polyphenols, Carotenoids and many other phytochemicals as they work as anti-oxidants in our system to prevent cell death
Several anti-oxidative compound and enzymes such as Glutathion, Super oxide dismutase, Catalase also work as auto anti-oxidants in our system
